Introdução à inferência causal em epidemiologia: uma abordagem gráfica e contrafatual / Introduction to causal inference in epidemiology: a graphic and counterfactual approach

Apresenta o desenvolvimento mais recente dos métodos de inferência causal utilizados em epidemiologia, em especial as abordagens contrafatual e gráfica, abordando temas como modelo de respostas potenciais para estimativas de efeitos causais via escore de propensão, gráficos acíclicos direcionados, computação G e análise de sensibilidade

Tuberculosis in the state of Alagoas: spatial and temporal analysis between 2010 and 2015 / Tuberculose no estado de Alagoas: análise espacial e temporal entre 2010 e 2015

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. Each year, more than 70 thousand new cases of the disease are registered in Brazil. The aim of this study was to analyze the tendency and the spatial distribution of tuberculosis in the state of Alagoas in the 2010-2015 period and to identify possible areas of under-reported cases or high risk of transmission. This was a mixed ecological study. Six indicators were analyzed: incidence of tuberculosis, incidence of bacilliferous pulmonary tuberculosis, mortality, HIV/TB coinfection, cure and treatment abandonment. In the temporal analysis, the regression model by inflection points (Joinpoint) was used to identify the APC (Annual Percentual Change) and the trends were classified as increasing, stationary and decreasing. In the spatial analysis, Local Empirical Bayesian Method and Global and Local Moran statistics were used. Significance adopted was 5% with a 95% confidence interval (CI 95%). There was a statistically significant tendency of reduction in the general rate of tuberculosis incidence (APC -5.6; p = 0.01) and the proportion of abandonment (APC -10.9; p = 0.048). However, the proportion of coinfection presented a growing tendency (APC 7.9; p = 0.01). The other indicators presented a stationary pattern. The Bayesian method reduced random data fluctuation. The Moran statistic showed a significant autocorrelation for the incidence of general and bacilliferous pulmonary tuberculosis, with a concentration in the Metropolitan Region of Maceió. Tuberculosis represents a major public health problem in Alagoas. The Mesoregion of the Alagoano Sertão (woodlands) appears as an area where under-reporting of cases occurs. The study demonstrated the need to strengthen actions to cope with the disease

A tuberculose é uma doença infectocontagiosa causada pelo Mycobacterium tuberculosis. A cada ano mais de 70 mil casos novos da doença são registrados no Brasil. Buscou-se analisar a tendência e a distribuição espacial da TB no estado de Alagoas no período de 2010 a 2015 e identificar áreas de possível subnotificação de casos ou de alto risco de transmissão. Trata-se de um estudo ecológico misto. Foram analisados seis indicadores: incidência de tuberculose, incidência de tuberculose pulmonar bacilífera, mortalidade, coinfecção HIV/TB, cura e abandono de tratamento. Na análise temporal, aplicou-se o modelo de regressão por pontos de inflexão (joinpoint) para a identificação do APC (Annual Percentual Change) e classificação da tendência em crescente, estacionária e decrescente. Na análise espacial, utilizou-se a Modelagem Bayesiana Empírica Local e a estatística de Moran Global e Local. Adotou-se significância de 5% e intervalo de confiança de 95% (IC 95%). Observou-se tendência estatisticamente significativa de redução da taxa de incidência de tuberculose geral (APC -5,6; p=0,01) e da proporção de abandono (APC -10,9; p=0,048). Por outro lado, a proporção de coinfecção apresentou tendência de crescimento (APC 7,9; p=0,01). Os demais indicadores apresentaram padrão estacionário. A modelagem bayesiana permitiu a redução da flutuação aleatória dos dados. A estatística de Moran mostrou auto correlação significativa para a incidência de tuberculose geral e pulmonar bacilífera, com concentração na Região Metropolitana de Maceió. A tuberculose representa um problema de saúde pública importante em Alagoas, uma vez que a Mesorregião do Sertão Alagoano se configurou como área de subnotificação de casos demonstrando-se, nesse sentido, a necessidade de fortalecimento das ações de enfrentamento à doença

Bioestatística e epidemiologia: perguntas que você sempre quis fazer, mas nunca teve coragem / Biostatistics and epidemiology: questions you always wanted to ask but never had the courage to

Dando continuidade aos artigos da série "Perguntas que você sempre quis fazer, mas nunca teve coragem", que tem como objetivo responder e sugerir referências para o melhor entendimento das principais dúvidas estatísticas levantadas por pesquisadores da área da saúde, este terceiro artigo aborda o contexto epidemiológico. Neste contexto, foram diferenciadas as principais medidas como prevalência, incidência, Odds Ratio (OR), Risco Relativo (RR), Razão de Prevalência (RP) e Hazard Ratio (HR), foi esclarecido o uso de análises por intenção de tratar e análise por protocolo, e também discutidos alguns dos termos comumente utilizados e pouco compreendidos como tipo de amostra, nível de evidência, relevância clínica e estatística, entre outros. (AU)

Continuing the series of articles "Questions you always wanted to ask but never had the courage to," which aims to answer key statistical questions raised by health researchers and suggest references for a better understanding, this third article addresses the epidemiological context. In this context, important measures such as prevalence, incidence, odds ratio (OR), relative risk (RR), prevalence ratio (PR) and hazard ratio (HR) were differentiated; the use of intention-to-treat analysis and per-protocol analysis was clarified; and some terms commonly used and poorly understood were discussed, such as type of sample, level of evidence, clinical and statistical relevance, among others. (AU)

Infecciones y anemia en estudiantes de la parroquia Guapán, Azogues, Ecuador / Infections and anemia in students of theGuapán parish, Azogues, Ecuador

Introducción: Las unidades educativas constituyen un entorno ideal para el diagnóstico de enfermedades y la promoción de salud. Objetivo:Identificar la presencia de enfermedades infecciosas y anemia en los estudiantes de la Unidad Educativa Ezequiel Cárdenas Espinoza de la parroquia Guapán del cantón Azogues en Ecuador y tomar medidas correctivas al respecto.Métodos:Se realizó un estudio observacional, descriptivo, transversal y prospectivo.El universo fueron los316 estudiantes matriculados enla Unidad Educativa Ezequiel Cárdenas Espinoza de la parroquia Guapán del cantón Azogues en Ecuador durante el periodo académico 2013-2014. La muestra fue coincidente pues setrabajó con todos los estudiantes de la institución en edades comprendidas entre 11 y 17 años de edad. Las variables evaluadas fueron edad, sexo y enfermedades más frecuentes para lo cual se utilizó como técnicas el coproparasitario, examen de sangre (hemoglobina), y examen elemental y microscópico de orina.Resultados:El 21.6% de los estudiantes evaluados presentaron parasitosis intestinal. La parasitosis más frecuente fue causada por Ameba histolytica con un 60% y 25% de Ascaris lumbricoides. El sexo predominantemente afectado fue el masculino con el 71%. Solo una estudiante del 8vo curso, correspondiente al 1.3% y un 5% de los estudiantes de 9no curso presentaron anemia. En todos los cursos se diagnosticaron estudiantes con infección de vías urinarias, representando el 15.2%. El 77.1% de los afectados fue del sexo femenino.Conclusiones:La presencia de enfermedades infecciosas y anemia determina el diseño de estrategias educativas a estudiantes, padres de familia y profesores de la institución

Introduction:The educational units constitute an ideal environment for diagnosing diseases and promoting health.Objective:To identify the presence of infectious diseases and anemia in the students of the Ezequiel Cárdenas Espinoza Educational Unit of the Guapan parish of the Azogues canton in Ecuador and to take corrective measures in this regard.Methods:An observational, descriptive, cross-sectional and prospective study was carried out. The universe was the 316 students enrolled in the Ezequiel Cárdenas Espinoza Educational Unit of the Guapan parish of the Azogues canton in Ecuador during the 2013-2014 academic period. The sample was coincident because it worked with all the students of the institution in ages between 11 and 17 years of age. The variables evaluated were age, sex and most frequent diseases for which coproparasitic, blood test (hemoglobin), and elementary and microscopic urine tests were used as techniques.Results:21.6% of the students evaluated presented intestinal parasitosis. The most frequent parasitosis was caused by Ameba histolytica with 60% and 25% of Ascaris lumbricoides. The predominantly affectedsex was male with 71%. Only one student in the 8th grade, corresponding to 1.3% and 5% of the 9th grade students, presented anemia. In all the courses, students with urinary tract infection were diagnosed, representing 15.2%. 77.1% of those affected were female.Conclusions:The presence of infectious diseases and anemia determines the design of educational strategies for students, parents and teachers of the institution.

How clinically important is the p-value? / Clinicamente que tan importante es el Valor-p?

Currently, it has been observed a growing number of publications in all fields of Dentistry. These publications act as scientific evidence, as well as a basis for clinical decision-making in dental care routine. It is important to note that the results and conclusions in articles are based on the p-value that is a purely probabilistic and statistical parameter, and it assists the researcher to accept or reject the null hypothesis being tested. The p-value was proposed by Fisher in 1925, and in Dentistry, it is usual to adopt the p-value stated in 0.05.1 In practical terms, when a statistical test results in p-value less than 0.05, the null hypothesis must be rejected (equality between groups), assuming that there is a difference between the assessed groups.2 In other words, p<0.05 indicates statistically significant difference between groups. Under a critical look, the researcher and reader should keep in mind that a statistical difference is not always reflecting a true clinical importance. In addition, a lack of statistical significance does not necessarily relate to the absence of clinical significance. The clinical importance is far beyond statistical calculations based on the p-value.3 A study presents clinical importance when the one being tested presents clinical effect capable to change the behavior of the dentist in daily routine. This judgment should be done by the researcher based on the results of his/her research, clinical experience and actual knowledge. In addition, estimates of effect sizes should be presented. This facilitates assessment of how large or small the observed effect could actually be in the population of interest, and hence how clinically important it could be. Kassab et al. (2006)4 compared periodontal parameters in groups with and without chemical biomodifciation of the root prior surgical coverage in cases of gingival recession. The group, that used edetic acid, statistically improved the periodontal parameters in relation to the group without surface biomodification. However, this difference was imperceptible to both dentist and patient. That is, the clinical result of root coverage will be the same when using or not acid biomodification of the root. In other words, there was not an important clinical effect of this step, although there was a significant difference. In the above example, it is clear that just because a statistic test is significant doesn't mean the effect it measures is significant or clinically important. Then, researchers

Epidemiologia, principais complicações e mortalidade dos pacientes atendidos em um Centro de Tratamento de Queimados na Amazônia / Epidemiologic profiles, major complications, and mortality rate at a burn treatment center in the Amazon

Introdução: São muitos os pacientes queimados que, apesar de um complexo tratamento multidisciplinar, são levados ao óbito. O objetivo deste estudo é determinar o perfil epidemiológico, ressaltando as principais complicações que acometem os pacientes queimados. Métodos: Estudo retrospectivo que analisou prontuários de pacientes queimados atendidos no Hospital Metropolitano de Urgência e Emergência no Estado do Pará, no período de janeiro de 2007 até dezembro de 2012. Resultados: A maioria dos pacientes era do sexo masculino (69,1%), entre 18 e 30 anos (35,5%), procedente de outros hospitais (35,8%), trabalhador da construção civil (21,2%). As complicações mais encontradas foram insuficiência respiratória (69,4%), insuficiência renal (57,1%) e sepse (38,8%). Conclusões: Os dados obtidos são similares aos encontrados na literatura nacional e internacional, evidenciando a necessidade de prevenção e fiscalização de trabalhadores da construção civil, bem como de implementar protocolos de tratamento para melhorar a assistência ao paciente queimado.

Introduction: Despite complex multidisciplinary treatment, many burn patients die. This study aimed to determine epidemiologic profiles of burn patients, highlighting major complications. Methods: This retrospective study analyzed the medical records of burn patients managed at the Metropolitan Hospital for Urgent and Emergent Care, Pará State, between January 2007 and December 2012. Results: most patients were males (69.1%) aged 18 to 30 years (35.5%), referred from other hospitals (35.8%), and employed as construction workers (21.2%). The most frequent complications were respiratory (69.4%) and renal failure (57.1%), followed by sepsis (38.8%). Conclusions: The data obtained were similar to those reported in national and international literature, highlighting the need for burn prevention and inspection of construction sites, as well as implementation of treatment protocols to improve care for burn patients.

Modelo epidémico para el estudio regional de la chikungunya / Epidemic Model for the regional study of chikungunya

En el presente estudio planteamos un modelo matemático como marco cuantitativo para describir el brote epidémico de la enfermedad de chikungunya ocurrido en Guatemala durante las últimas semanas del 2014. El modelo pertenece a la familia de modelos compartimentales, introducidos inicialmente para el estudio epidemiológico de la malaria. Contiene los ingredientes básicos para describir la dinámica de transmisión del virus entre las poblaciones de humanos y mosquitos. El trabajo inicia con un análisis teórico cuyo objetivo es mostrar la estabilidad del modelo y explorar las posibilidades de equilibrio endémico y equilibrio libre de la infección en una población dada. Luego del análisis de estabilidad, se interpretó la incidencia semanal de humanos infectados predicha por el modelo como el valor esperado de las observaciones. Para ello se tomaron en cuenta los datos oficiales reportados durante el 2014 en las memorias epidemiológicas del Ministerio de Salud Pública y Asistencia Social de Guatemala (MSPAS), correspondientes a cuatro municipios del departamento de Escuintla. En cada caso, se realizó una simulación numérica, utilizando métodos estadísticos que permiten obtener el mejor ajuste de parámetros biológicos y poblacionales del modelo frente a los datos reportados por el MSPAS. La simulación permitió caracterizar los registros observados en cada localidad a la luz del modelo en discusión. Los métodos presentados en este trabajo podrían ser útiles como herramienta cuantitativa de apoyo para prever escenarios futuros sobre epidemias regionales de enfermedades ocasionadas por el Aedes aegypti, tales como el dengue, el zika y la chikungunya.

In the present study we propose a quantitative framework to describe the epidemic outbreak of chikungunya disease occurred in Guatemala during the last weeks of 2014. The model belongs to the family of compartmental models, initially introduced for the epidemiological study of malaria. It contains the basic ingredients to describe the dynamics of virus transmission between human and mosquito populations. The study begins with a theoretical analysis aimed at showing the stability of the model in order to explore the possibilities of endemic balance and free balance of the infection in a given population. Once the stable equilibrium points were identified, the weekly incidence of infected humans estimated by the model was considered as the expected value of the observations. To this end, the official data reported during 2014 by the Ministry of Public Health and Social Assistance of Guatemala (MSPAS), corresponding to four municipalities in the department of Escuintla were taken into account. In each case, a numerical simulation was performed using statistical methods that allow obtaining the best fit of biological and population parameters of the model compared to the data reported by the MSPAS. The simulation enables to characterize the records observed in each locality on the grounds of the model under discussion. The quantitative methods presented in this paper could be useful for predicting.

Conceptos estadísticos para interpretar un trabajo de investigación / Statistical concepts to understand a research work

Teniendo en cuenta la importancia de la bioestadística en los trabajos de investigación destinados a los profesionales de atención primaria, se describen dos de sus conceptos básicos: medidas de tendencia central y medidas de dispersión...